1. Field of the Invention
The present invention relates to a bump structure and a manufacturing method thereof, and more particularly to a bump structure with an annular support and a manufacturing method thereof.
2. Description of Related Art
Flip chip interconnect technology is a packaging technique for connecting a die to a circuit board, which is mainly conducted by forming a plurality of bumps on respective pads of the die, flipping the die over, and connecting the pads of the die to terminals on the circuit board via the bumps, such that the die is electrically connected to the circuit board through the bumps. In general, the bumps are of various types such as solder bumps, gold bumps, copper bumps, conductive polymer bumps, polymer bumps, and so forth.
FIG. 1A is a cross-sectional view of a conventional gold bump, while FIG. 1B is a top view of the conventional gold bump. Referring to FIGS. 1A and 1B, a conventional gold bump structure is adapted to be disposed on a die 110 on which a plurality of aluminum pads 120 (only one aluminum pad shown in FIGS. 1A and 1B) and a passivation layer 130 are formed. The passivation layer 130 has a plurality of openings 130a exposing a portion of each of the aluminum pads 120, respectively. In addition, the conventional gold bump structure includes an under ball metal (UBM) layer 140 and a gold bump 150. The UBM layer 140 is disposed within the opening 130a and covers a portion of the passivation layer 130. The gold bump 150 is disposed on the UBM layer 140. The gold bump 150 covers the UBM layer 140 over the portion of the passivation layer 130, resulting in formation of an annular protrusion 150a of the gold bump 150. This is called a wall effect. The annular protrusion 150a may pose an impact on the bonding strength between the gold bump 150 and other carriers (not shown). Moreover, the UBM layer 140 is disposed right below the gold bump 150. Accordingly, as cracks are formed between the UBM layer 140 and the gold bump 150, or, between the UBM layer 140 and the passivation layer 130, an under cut effect on the conventional gold bump structure can often be expected.